Nacho Moreno-Suarez,PhD-candidate in Exercise PhysiologySchool of Physiotherapy & Exercise Sciences, Curtin University

Associate Professor Andrew MaioranaCurtin University;Advanced heart failure & cardiac transplant Service & Allied Health Department, FSH

A Comparison of different intensity exercise training in Patients with Left Ventricular Assist Devices

Background

• Left ventricular assist device (LVAD). • Electro-mechanical pump implanted into the

left ventricle to augment cardiac output.

• A treatment option for patients with advanced heart failure (HF).Bridge-to-transplantDestination therapy

• Associated with:↑ Survival↑ Exercise capacity↑ Quality of life

Background VO2peak remains reduced

• As low as 50% of age-predicted values 1,2

• Lower than heart-transplanted patients 3

Very few studies have evaluated the efficacy of exercise training in patients with LVADs.

Currently there are no specific exercise prescription guidelines for this patient population.

1. Simon, J Heart Lung Transplant. 2005.2. Allen, J Heart Lung Transplant. 2010.3. Slaughter, N Engl J Med. 2009.

High intensity training in heart failure without LVAD

• High-intensity interval training (HIIT) was safe for patients with HF (but no LVAD).• May be superior compared with traditional moderate-intensity-continuous training (MICT)4

No study has tested HIIT in patients with LVADs!4. Gomes-Neto et al., Int J Cardiol. 2018

Objective

To evaluate the safety and efficacy of 12-week exercise training program of HIIT vs. MICT (usual care) in

patients with LVADs

Methods

• Ethical and site-specific approvals were granted• ANZCTR Registration (ACTRN12616001596493)

HIIT MICT

LVAD implantation

Routine Rehabilitation >6 weeks

Baseline Assessments

Randomisation

Follow up at 12 weeks

Study design

Methods: AssessmentsPrimary Outcome

• Cardiopulmonary Exercise Testing VO2peak using Modified Naughton

protocol on treadmill

Secondary Outcomes

Functional Capacity 6-minute walk test (6MWT).

Vascular Endothelial Function Flow-mediated dilation (FMD%) of brachial artery

Resting Peak diameter

Exercise Training Interventions

• 12-week Exercise Program• 3 sessions per week

• All sessions commence and concluded with 5-min aerobic exercise and stretching

• Identical Resistance Exercise• Consistent with best-practice for

cardiac rehabilitation

• Aerobic Exercise (Randomised)• MICT (50-60% VO2 reserve)• HIIT (80-90% VO2 reserve, 4x4

minutes)

Aerobic Exercise Protocol

0

20

40

60

80

100

0 5 9 13 17 21 25 29 33

Exer

cise

Inte

nsity

(%

VO

2 re

serv

e)

0

20

40

60

80

100

0 5 9 13 17 21 25 29 33

Exer

cise

Inte

nsity

(%

VO

2re

serv

e)

4-mininterval

3-min active recovery

5-min warm up

MICT(usual care)

28-min steady-state intensity

HIIT

5-min warm up

Time (minutes)

Methods: Statistical Analyses

• At baseline, comparison between groups was carried out using independent Student t-test or Mann-Whitney U-test.

• To compare the effects of exercise training:• Linear mixed models (LMM) with random subject effects.

• All analyses were 2-tailed & p < 0.05 considered significant.

• Data was analysed in Stata 14 software.

Assessed for eligibility (n = 28)

Excluded (n = 7)- Did not meet inclusion criteria (n = 2)- Received cardiac transplant (n=2)- Declined to participate (n = 3)

Completed (n = 8)

Lost to follow-up (n = 3)- Received cardiac transplantation (n=2)- Discontinued intervention (n=1)

HIIT intervention (n = 11)

Lost to follow-up (n = 2)- Received cardiac transplantation (n=2)

MICT intervention (n = 10)

Completed (n = 8)

Allocation

Analysis

Follow-Up

Randomised (n = 21)

Enrollment

Results: CONSORT

Results: Baseline characteristics

Characteristic HIIT group (n=11) MICT group (n=10) p-value

Age (years) 57.7 ± 13.1 55.6 ± 14.2 0.736

Weight (kg) 83.6 ± 14.9 82.6 ± 13.0 0.908

BMI (kg/m2) 27.3 ± 4.2 29.0 ± 4.4 0.376

Female sex (%) 27% 50% 0.290

Time since LVAD implantation (days) 91 [59 - 362] 125 [60 - 447] 0.885

No significant differences at baseline

Results: Safety of Exercise

There were no serious adverse events during testing, or during the intervention period in either group.

One participant experienced supraventricular tachycardia during a MICT session.

• Event was not severe enough to interrupt continuation in the trial

Results: VO2peak

Mean difference between groups (HIIT - MICT) = 1.9 mL·kg-1·min-1

(95%CI: 0.3 to 4.2)

MICT ↑ 1.0 mL·kg-1·min-1

(95%CI: -0.9 to 2.7)HIIT ↑ 2.9 mL·kg-1·min-1

(95%CI: 1.4 to 4.0)

Results: 6-Minute Walk Test

Mean between-group difference = 27 m (95%CI: -18 to 73)

HIIT group ↑ 90 m (95%CI: 41 to 138)

MICT group ↑ 63 m (95%CI: 36 to 88)

No between group mean difference =-0.8% (95%CI: -2.4 to -0.9)

HIIT ↑ 0.7% (95%CI: -1.0 to 2.5)

Results: FMD (%)

MICT ↑ 1.6% (95%CI: 0.2 to 3.1)

Baseline

Follow-up

N.S

Conclusion & Clinical Implications

• HIIT appears to be safe and well-tolerated among patients with LVADs.

• HIIT improved cardiorespiratory fitness more than MICT. MICT traditional approach in exercise rehabilitation.

• Preliminary findings support the prescription of HIIT in clinically stable patients with LVADs.

• But warrant validation in larger trials & across a broader range of physiologic and clinical outcomes.

Acknowledgements

Co-investigators: Ms Anna Scheer Dr Kaitlyn Lam Dr Robert Larbalestier Dr Lawrence Dembo A/Prof Andrew Maiorana

The Advanced Heart Failure & Cardiac Transplant Service team at FSH

The patients

Sponsors

Questions?

Thanks for your attention!